He is wrong, transphobia has no place anywhere. Trying to pass it under the thin guise of "unfair moderation" is both cowardly and thinly veiled. It certainly has no place in the workplace. Would he try to deny the identify of our trans senior developer? Would he say discriminatory things about our trans in house counsel? He has already shown from this blog he has transphobic beliefs and no problem saying discriminatory statements.
Beyond being an ethically bad and bigoted person, this guy would bring state and federal liability to the company from the first day on the job. I don't care if he disagrees, this isn't a matter up for discussion, I will not break the law for you.